Other mistake: Throughout many episodes, it's discovered that anybody that touches Death immediately dies. When Stewie learns that Death has come for Peter, he immediately touches his finger to lead him inside but manages to live.

Lois: Hello?Peter: I can't take the trash out today, I'm working late at the office.Lois: The caller ID says you're calling from the kitchen. In fact I can see you.Peter: [Edging sideways.] OK, can you see me now?Lois: No.Peter: Now I am at the office.

They're in the Clam complaining that they can't drink when they make the revelation that Brian can because he's technically 56. But Quagmire should be able to drink, as in a much earlier episode, he's revealed to be over 60.